Recovery of lithium from brines

ABSTRACT

Lithium is preferentially extracted from brine containing Li salts along with salts of other metals, e.g. Na, Ca, Mg, K, and/or B, by contacting the brine with a particulate anion exchange resin having suspended therein a microcrystalline form of LiX.2Al(OH)3, where X = halide.

CROSS-REFERENCE TO CO-FILED APPLICATION

a related invention is disclosed in our co-filed application Ser. No.812,534, filed July 5, 1977.

BACKGROUND OF THE INVENTION

Various brines exist which contain Li salts. At times, it is desired topreferentially remove and/or recover the Li ion from the brine. In somebrines, such as geothermal brines or such as Smackover brines, it isoften desirable to remove Li values therefrom, either because one wantsthe Li values in substantially pure or concentrated form or because onewants the brine to be substantially free of Li.

There are various published articles and patents dealing with Liextraction from brines.

In Israel J. Chem. Vol. 1, 1963 (pp. 115-120) there is an article by D.Kaplan titled "Process For The Extraction of Lithium From Dead SeaSolutions." There it is taught that Li is precipitated as lithiumaluminate from Dead Sea brines by adding an aluminum salt and an alkalithereto.

There is a U.S. Government Publication, PB 245,686, prepared by HazenResearch, Inc. for the U.S. Department of Interior, Bureau of Minesdated June 12, 1975 and distributed by National Technical InformationService, U.S. Department of Commerce, which is titled "The Recovery andSeparation of Mineral Values From Geothermal Brines". The articleteaches among other things, the use of aluminum hydroxide as aprecipitant for extracting Li from brine. The article also refers toU.S. Pat. Nos. 3,307,922; 3,306,712; 3,537,813; 2,964,381; and3,306,700.

U.S. Pat. No. 3,307,922 teaches the use of an immiscible monoalkanol orketone along with ammonia to separate lithium salts from calcium saltsin a brine solution.

U.S. Pat. No. 3,306,712 is similar to U.S. Pat. No. 3,307,912 aboveexcept that it teaches the use of a complexing agent, e.g. urea, to formsoluble complexes with the calcium in the brine.

U.S. Pat. No. 3,537,813 involves the use of a metal halide (e.g., iron,cobalt, nickel) to react with lithium in brines, adding acid to avoidhydrolysis of the metal halide, and extraction of the lithium-containingcompounds into a water-insoluble organic solvent.

U.S. Pat. No. 2,964,381 teaches to separate lithium values from anaqueous solution which contains alkaline earth metal salts, by adding asoluble aluminum salt to precipitate the lithium as a lithium aluminatecomplex.

U.S. Pat. No. 3,306,700 enlarges on, and improves, the lithium aluminatecomplex process of U.S. Pat. No. 2,964,381 above.

Other patents which also help establish the state of the art ofextracting lithium values from brines are, e.g., U.S. Pat. Nos.2,980,497; 2,980,498; 2,980,499; 3,295,920; and 3,268,290.

U.S. Pat. No. 2,980,497 discloses a method of recovering the lithiumfrom a lithium aluminate complex formed, e.g., in the process of U.S.Pat. No. 2,964,381. The method involves heating the complex in water toat least 75° C. to decompose it and then using a strongly acidic cationexchange resin to bind the soluble lithium compound and impurities,subsequently treating the resin with a caustic solution to form solublelithium hydroxide and insoluble impurities and recovering the lithiumhydroxide.

U.S. Pat. No. 2,980,498 shows recovering of lithium values from ores(spodumene, lepidolite, and the like) by using a strongly acidic cationexchange resin in the acid form to obtain an ion exchange of the lithiumfrom the ore. The Li-containing resin is separated from the ore materialand the Li is recovered from the resin by e.g., eluting with caustic toget lithium hydroxide. The resin may then be regenerated with an acid torevert back to the acid form.

U.S. Pat. No. 2,980,499 shows improvement over U.S. Pat. No. 2,980,498above, by contacting the ore with the strongly acidic cation exchangeresin at a temperature between 95° C. and 150° C.

U.S. Pat. No. 3,295,920 shows improvement over U.S. Pat. No. 2,980,499above by contacting the ore and the ion exchange resin in the presenceof an aqueous solution containing about 10 to 80% of acetic or propionicacid.

U.S. Pat. No. 3,268,290 shows recovering Li values from sludge whichcomes from certain electrolytic processes for magnesium production. Thelithium recovery involves the use of a short-chain aliphatic monohydricalcohol, heat and agitation to dissolve the Li away from the othercomponents of the sludge, then evaporating the alcohol to obtain LiCl.

It can be seen, then, that there is a recognized need for methods ofrecovering Li from brines or other aqueous mixtures and solutions whichcontain metal values other than Li.

The art teaching the formation of lithium aluminate complexes and theuse of cation exchange resins to remove Li values from aqueous brines isbelieved to be the art most pertinent to the present invention.

It is an object of the present invention to provide an ion exchangemethod of preferentially removing Li values from brines wherein the ionexchange material is long-lived and does not require acid treatment torevert it to the acid form.

Another object is to provide an ion exchange method for preferentiallyrecovering Li values from brines which also contain other metal values.

A further object is to provide an ion exchange resin having incorporatedtherein LiX.2Al(OH)₃ which, after having LiX partially removed and thencontacted with brines containing Li salt and other metal salts, willpreferentially form a complex with the Li salt while substantiallyexcluding the other metal salts.

Yet another object is to incorporate LiX.2Al(OH)₃ in an anion exchangeresin in such fashion that Li⁺ may be cyclically removed from brine bythe resin and then eluted from the resin, the cycle being performednumerous times before encountering appreciable loss of exchangecapacity.

SUMMARY OF THE INVENTION

An anion exchange resin is treated with AlCl₃, then with ammonia tochange the AlCl₃ to Al(OH)₃. The resin, containing the Al(OH)₃ dispersedin it, is treated with aqueous LiX (where X is halide) and heated for atime sufficient to create a microcrystalline form LiX.2Al(OH)₃ dispersedin the resin. This novel form of resin is useful in preferentiallyrecovering Li⁺ from brines, including brines which contain Mg⁺⁺. Theresin may be cycled numerous times before encountering appreciable lossof exchange capacity. As used herein, the term "microcrystalline" isused to indicate small crystals (formed in small pores, voids, andspaces in the resin) which are detectable by X-ray diffraction, if notby a microscope.

DETAILED DESCRIPTION OF THE INVENTION

In general, the novel composition disclosed here is an anion exchangeresin containing LiX.2Al(OH)₃ dispersed or suspended within the resinparticles. Throughout this disclosure, LiX refers to lithium halides,especially LiCl. The expression "suspended therein" when referring tocompounds dispersed in the resin, means that the compounds are dispersedwithin the polymer matrices, not merely clinging to the externalsurfaces of the polymers.

The novel process disclosed here comprises contacting the anion exchangeresin, containing Al(OH)₃ dispersed within the resin particles, with aLi⁺ - containing (but Mg⁺⁺ - free) brine and heating it thereby forminga microcrystalline form of LiX.2Al(OH)₃ dispersed in the resin particle,and eluting a portion of the LiX out of the resin with water containinga small amount of LiX. The resin containing the LiX.2Al(OH)₃, with aportion of the LiX removed, is usable to remove more Li⁺ from brines,including brines which contain Mg⁺⁺.

The anion exchange resin with which one starts, may be any particulatewater-insoluble polymeric resin which contains basic amine groupsattached to the polymeric resin. Macroporous anion exchange resins arepreferred over the gel-type resins.

By "macroporous", as the term is commonly used in the resin art, it isgenerally meant that the pores, voids, or reticules are substantiallywithin the range of about 200 to about 2000 A. Another term, meaning thesame thing is "macroreticular."

Of particular interest are macroporous anion exchange resins sold asDOWEX (a trademark of The Dow Chemical Company) MWA-1 as the chlorideform of a particulate polystyrene highly crosslinked with divinylbenzenehaving --CH₂ N(CH₃)₂ groups attached to the benzene rings. These resinshave a particle size, generally, of about 20-50 mesh (U.S. StandardSieve size) and about 30-40% porosity with an internal surface area ofabout 30-50 m² /gm. Thus, each particle is a reticular solid containingpores of about 200-800 A in size. The base capacity is about 4.2-4.3meq./gm. of dry resin in its basic (or free amine) form. The basestrength, as measured by a glass electrode in 26% NaCl, is pK_(b) = 4 ×10⁻⁷ (mid-point in acid-base titration curve is pH = 7.6).

Other resins of particular interest are, e.g., those similar to DOWEXMWA-1, with the amine group being --CH₂ NRR' where R and R' may be,individually, a hydrogen or alkyl group of 1-4 carbon atoms. Also,resins containing other amines or amino groups (tertiary, primary,secondary, cyclic) are within the purview of the present invention.

Other exchange resins which may be employed may be any anion exchangeresins with a base strength greater than pK_(b) = 1 × 10⁻⁷, withmacroporous resins being preferred, e.g. Amberlyst A-21.

The Kirk-Othmer Encyclopedia of Chemical Technology, vol. 11, pp.871-899 on the subject of "Ion Exchange", including discussions ofcommercially available anion exchange resins, is a helpful reference.Another helpful reference is a book titled "Ion Exchange" by FriedrichHelfferich published by McGraw-Hill, 1962.

Detailed information about pore sizes of "gel-type", "microreticular",and "macroreticular" ion exchange resins may be found in "Ion Exchangein The Process Industries" published in 1970 by The Society of ChemicalIndustry, 14 Belgrave Square, London, S.W.I, England.

Among the macroporous anion exchange resins, which are within thepurview of the present invention are: strongbase resins containingquaternary ammonium groups fixed to a poly (styrene-divinylbenzene);poly (vinyltoluene) which has been side-chain chlorinated and reactedwith a tertiary amine to form a quaternary ammonium salt; or any of thewater-insoluble, but water-swellable aromatic polymers containingquaternary ammonium groups such as those named in the market place asDowex MSA-1. Other macroporous strong-base resins are, e.g., AMBERLYSTA-26 and 27.

Also gel-type anion exchange resins which contain primary, secondary,tertiary amine and quaternary ammonium groups are operable, such asAmberlite IRA-400, Amberlite IRA-401, Amberlite IRA-402, AmberliteIRA-900, Duolite A-101-D, Duolite ES-111, Dowex 1, Dowex 11, Dowex 21K,Ionac A540, Dowex 44, Duolite A-7, Ionac A-260 and Amberlite IRA-68.Such commercial resins are discussed and described in the literature,such as in the Kirk-Othmer Encyclopedia of Technology and productbrochures.

In determining the efficacy of an exchange resin for use in the presentinvention, particulate macroporous resins which have a porosity of atleast about 15%, an internal surface area of at least about 10 m² /gmand a base capacity of at least about 2.0 meq./gm. (dry, basic form) arepreferred.

Such resins, if obtained in the base form, are preferably converted tothe chloride-form prior to being contacted with the aq. AlCl₃. This isconveniently done by treating the amine-form, This is conveniently doneby treating the amine-form, under reduced pressure, with an excess ofaqueous HCl, then filtering, washing and draining off the water. Apressure differential across the filter may be employed to speed thedraining process, if desired.

The AlCl₃ which is used in treating the chloride-form of the resin isconveniently, and preferably, a saturated aqueous solution containingabout 31% to about 32% AlCl₃ though weaker concentrations are operable,giving less capacity. Hydrates of AlCl₃, such as AlCl₃. 6H₂ O, areuseful in preparing the aqueous solutions.

Outlining the overall preferred steps, generally, used in preparing theLiX.2Al(OH)₃ - containing resin and employing it to recover Li⁺ valuesfrom brine:

1. Impregnate an anion exchange resin with aqueous AlCl₃ ;

2. Treat the AlCl₃ - impregnated resin with aqueous NH₃ to convert theAlCl₃ to Al(OH)₃ ;

3. Treat the resulting Al(OH)₃ - containing resin with aqueous Li halideto provide halolithium aluminate or lithium aluminate dispersed in theresin;

4. Heat the resin, containing the so-formed aluminate, at a temperatureand for a time sufficient to form microcrystalline LiX.2Al(OH)₃dispersed in the resin and adjust the pH, if needed, to within the rangeof about 6.0 to 7.5 in saturated NaCl brine;

5. Elute a portion of the Li⁺ values from the resin by employing a weaksolution of LiX;

6. Contact the resin, containing the partially LiX-depletedmicrocrystalline LiX.2Al(OH)₃ dispersed therein, with a Li⁺ -containingbrine to selectively remove the Li⁺ from the brine;

7. Repeat steps 5 and 6, sequentially, a plurality of times.

Ordinarily, a cubic foot of resin prepared by the present invention,will contain about 3 to about 12 pounds of microcrystallineLiX.2Al(OH)₃, or stated another way, about 50 to about 200 gms./liter ofresin.

The above steps are described in greater detail by the followinggeneralized embodiments:

STEP I

The anion exchange resin with which one starts may be impregnated as iswith aqueous AlCl₃ or may be first converted to its chloride form bybeing treated with aqueous HCl. The anion exchange resin may be of the"weak base" or "strong base" type, normally containing pendant amine, orquaternary ammonium groups attached to a polymeric structure. If it isdesired to convert the basic form of the resin to the chloride form,this may be done, e.g., by contacting the resin with aqueous HCl (of,say, 5-10% concentration). Ambient temperature may be used for the HCltreatment, though slightly increased temperature may also be used. Inorder to completely "soak" the resin, a reduced pressure is usuallyhelpful during the HCl treatment. An aqueous solution of AlCl₃ isimpregnated into the resin, whether the resin is in its basic form orits chloride form. The aqueous AlCl₃ is preferably concentrated, with asaturated solution of about 31-32% AlCl₃ being most preferred. Theamount of aq. AlCl₃ used should be enough to substantially replace allthe liquid which was already in the resin and still have enough tocompletely flood the resin. The excess aq. AlCl₃ is then drained,leaving a resin which is moist; the remaining moisture may be removed,e.g., by flowing hot, dry inert gas or air through the resin, but thisis not necessary. Ambient temperature is operable for this step, thoughincreased temperature may be used to speed the process.

An alternative method of impregnating the resin with AlCl₃ is to addAlCl₃ to a resin/water mixture, but it is generally preferred to flowconcentrated aq. AlCl₃ through a column bed of resin, thereby replacingthe liquid in the resin with the aq. AlCl₃.

STEP II

The AlCl₃ -containing resin is then treated with ammonia, preferablyaqueous ammonia, NH₄ OH, to convert the AlCl₃ to Al(OH)₃ within theresin particles. Ambient temperature is operable, though increasedtemperature may be used to speed the process. Generally, it is best toemploy an excess of NH₄ OH to be assured of rapid and completeconversion of the AlCl₃ to Al(OH)₃. The excess NH₄ OH may be drained offand it is generally best to flush with enough H₂ O or NaCl brine tosubstantially remove the NH₄ OH, NH₄ Cl and any Al(OH)₃ which may haveformed outside the resin particles.

NH₄ OH is preferred over the use of NaOH or KOH or other strong alkalibecause the strong alkalis tend to form water-soluble alkali aluminates,such as sodium aluminate, and these soluble aluminates would then bemore easily washed from the resin than the Al(OH)₃ precipitated by usingNH₄ OH. The quantity of NH₄ OH to be used is equivalent to the AlCl₃according to the equation

    3 NH.sub.4 OH + AlCl.sub.3 →Al(OH).sub.3 + 3 NH.sub.4 Cl

plus the amount required to convert the resin to its basic form(assuming that all the resin was converted to the chloride form in Step1.) The preferred amount is a several-fold excess of concentrated aq.NH₄ OH over the above minimum amount. The volume of the NH₄ OH should beas much as is needed to achieve uniform wetting of the resin particlesthroughout. Preferably at least about 0.5-1.0 part by weight of conc.NH₄ OH solution (e.g. about 30% NH₃) is used per part of AlCl₃ -containing resin. The Al(OH)₃ so-obtained is an "active" Al(OH)₃ whichwill readily absorb LiX from brine solutions; X-ray diffraction patternanalysis indicates this Al(OH)₃ has little or no crystallinity.

An alternate, but not preferred, method of converting the AlCl₃ toAl(OH)₃ is to treat the thoroughly wetted AlCl₃ - containing resin withNH₃ gas or NH₃ diluted with air or other inert gas.

STEP III

The active Al(OH)₃ - containing resin from Step 2 is then treated, at pH6.0 or higher, with an aqueous solution of lithium halide, especiallyLiCl. The aqueous solution may be a Li⁺ - containing brine which isMg⁺⁺ - free. The Li halide combines with the Al(OH)₃ to give ahalolithium aluminate or lithium aluminate which, by X-ray diffraction,is found to have little or no crystallinity. If the lithiumaluminate-resin mixture is employed, without the heat treatmentdescribed below, to remove Li⁺ from brines, it must be reconstructedafter one cycle, the residual non-active Al(OH)₃ removed, re-impregnatedwith AlCl₃ and then again treated with NH₃ to regain the active Al(OH)₃form. It is preferred that the amount of LiX be an amount in excess ofthat required to complex with the Al(OH)₃ to form the structureLiX.2Al(OH)₃ in Step IV.

STEP IV

According to the present invention the lithium aluminate-resin, orhalolithium aluminate- resin, is heated at an elevated temperature for atime sufficient to convert the aluminate compound to a microcrystallineform having the formula LiX.2Al(OH)₃, where X = halide, the crystalstructure of which is found to exhibit essentially the same X-raydiffraction pattern as the aluminates prepared according to Goodenoughand by Lejus et al.

Formation of a crystalline chlorolithium aluminate is reported byGoodenough and confirmed by X-ray (U.S. Pat. No. 2,964,381). X-raystudies of such compounds are reported by Anne Marie Lejus et al ine.g., Compt. Rend. vol. 254 (1962) and in Rev. Hautes Temper. etRefract. t. I, 1964, pp. 53-95.

Preferably the elevated temperature is from at least about 50° C. up tothe reflux temperature of the mixture, there being enough water presentto provide a refluxing portion while maintaining the resin thoroughlywetted during the heating. Ordinarily the time of heating for thetemperature range of 50°- reflux will be about 1 hour to about 16 hours.Insufficient heating or insufficient time of heating may result inhaving some of the aluminate compound not converted to themicrocrystalline form, thereby reducing the cyclable capacity of theresin.

If not enough LiX has been employed in Step III to complex with all theactive Al(OH)₃ then some crystalline Al(OH)₃ may be formed during thisStep IV heating step and not form the desired LiX.2Al(OH)₃. Suchcrystalline Al(OH)₃, e.g. Bayerite, Gibbsite, Norstrandite, or mixturesof these, are not effective in absorbing LiX from brine in the presentinvention. Thus, it is preferred that substantially all the active(freshly prepared) Al(OH)₃ be complexed with excess LiX and then heatedto form microcrystalline LiX.2Al(OH)₃ in order to attain or approach themaximum cyclable capacity. A 26% NaCl brine containing at least about300-1000 mg/l Li⁺ is suggested for use in this step.

STEP V

A portion of the Li⁺ values are eluted from the resin using an aqueouswash, preferably containing a small amount of lithium halide, e.g.,LiCl. The concentration of lithium halide in the elution liquor ispreferably in the range of about 300 to about 1500 ppm. An aqueouselution liquor may be employed which does not contain lithium halide ifthe elution is done batchwise with only enough water to remove a portionof the LiX from the resin composition, but is not preferred since thismay reduce the amount of LiX in a given crystal to less than the amountrequired to maintain the crystal integrity (crystals may change toNorstrandite and/or Bayerite). It is best, then, to employ at least asmall amount of lithium halide in the eluting liquor especially incolumn operation, to assure that not all, preferably not more than half,the lithium halide in the microcrystalline LiX.2Al(OH)₃ is removed. Theelution step is best done at elevated temperatures above about 40° C.,preferably about 50° C. to reflux temperature.

STEP VI

This step is done, e.g., by contacting the Li⁺ - containing brine withthe partially eluted LiX.2Al(OH)₃ - containing resin from Step V in acolumn bed by flowing the brine through until the Li⁺ conc. in theeffluent approx. equals the Li⁺ conc. in the influent. Loading rate isenhanced if the temperature of the brine is above about 40° C.,preferably about 50° C. to reflux, most preferably about 80°-108°.Higher temperatures, requiring superatmospheric pressures, requireequipment capable of withstanding the pressure.

STEP VII

Steps V and VI are repeated, sequentially, a plurality of times.

The resin, containing the microcrystalline LiX.2Al(OH)₃ is re-usablenumerous times in a cycling process where Li⁺ -containing brine, evenbrine containing Mg⁺⁺, is contacted with the resin to recover Li⁺ fromthe brine, then the Li⁺ values are eluted from the resin using a weakconcentration of aq. lithium halide.

EXAMPLE 1 (Preparing the resin/LiCl.2Al(OH)₃)

The product is prepared in the following way: 40.0 gms of Dowex MWA-1(in dry chloride form) is poured into a solution of 12.0 gms. AlCl₃.6H₂O in 60 gms H₂ O. With hand stirring, using a spatula, uniformly dampparticles result. This product is dried at room temperature in a streamof dry air to a weight of 52.67 gms. This free-flowing product is pouredinto a solution of 55 ml. NH₄ OH of 8.2% NH₃ conc. and mixed as beforeto uniformly damp particles. Five minutes later it is mixed with 500 mlof 7.0 pH Mg⁺⁺ -free Smackover brine containing 15.8% NaCl, 9.1% CaCl₂,and 305 mg/liter Li⁺ and warmed to 56° C. for 45 minutes. The brine isfiltered off and found to contain 55 mg/l Li⁺. Product is mixed with 500more ml of fresh brine and warmed to 70° C. over a period of 45 minutesand filtered, with filtrate analyzing 215 mg/liter Li⁺. An additional500 ml of brine is mixed with the product and refluxed for 16 hours. Thefinal filtrate contains 280 mg/liter Li⁺. Thus, the "sucked" dry productcontains 182.5 mg Li⁺. The bulk or settled volume of product is 136 ml.The pore volume is estimated to be 36 ml, which would be filled withfinal filtrate containing 10.1 mg Li⁺. Hence, the resin particlescontain 172.4 mg Li⁺ = 0.025 mols Li⁺. 12.0 gms AlCl₃.6H₂ O isequivalent to 0.050 mols Al(OH)₃. Hence, the final product contains 1mol Li/2 mol Al. The crystallinity of the compound, denoted here asLiCl.2Al(OH)₃ is confirmed by X-ray diffraction analysis.

EXAMPLE 2 (Recover Li⁺ - from brine)

The use of the product of Example 1 above is shown here for recoveringLi⁺ from brine:

116 ml of Product from Ex. 1 is put in a water jacketed burette columnto produce a resin bed 73 cm in depth. Product as made is saturated withLi⁺, so it is transferred into the column in 7.0 pH Mg-free Smackoverbrine (containing 305 mg/liter Li⁺). Each cycle then consists of elutionfollowed by brine resaturation. 8 cycles are run with downflow of 6.4ml/min. on water and brine, and all at 85°-90° C. water jackettemperature. When idle (e.g., 5 days between Cycle 5 and 6) the columnis left in the brine saturated state and allowed to cool to roomtemperature. Excessive water washing of earlier products had resulted ininactivation of the LiCl.2Al(OH)₃, so a limited quantity of water isused (250 ml on Cycles 1-5, inclusive and 200 ml on 6-8, inclusive) anda small quantity of LiCl is added to the water to limit further thereduction in Li⁺ content of the resin (0.15% LiCl in Cycles 1 and 2,0.06% LiCl in Cycles 3-8, inclusive). In each cycle 400 ml of brinefollows the water elution. This is about 125 ml more than required forLi⁺ saturation. The first 5 cycles were Mg⁺⁺ -free Smackover brinehaving 305 mg/liter Li⁺ at pH 7.0. The remaining cycles were withSmackover brine containing 305 mg/liter Li⁺ and 0.31% Mg⁺⁺ at pH 6.0. Inthe 6th cycle the effluent is caught in a series of 18 receivers: 25 mlin cuts 1-12, inclusive, and 50 ml in cuts 13-18, inclusive. These cutsare then analyzed for Li⁺ content by flame photometry. The analyses forCycle 6 are:

    ______________________________________                                        Cut No.  mg/l Li.sup.+                                                                             Cut No.    mg/l Li.sup.+                                 ______________________________________                                        1        280         10         145                                           2        287         11         85                                            3        380         12         0                                             4        1220        13         5                                             5        700         14         20                                            6        345         15         35                                            7        245         16         210                                           8        195         17         285                                           9        165         18         305                                           ______________________________________                                    

Integration of the results shows Li⁺ removal and recovery of 57.9 mg,which is 39.5% of the Li⁺ on the resin. Had the brine feed been limitedto 275 ml, as required for Li⁺ saturation, the recovery of Li⁺ is 69%from the brine. The average Li⁺ content of the water eluant is 430.7 mgLi/liter = 0.26% LiCl. The peak Li⁺ observed in the product (1220 mg/l)is 4 times the brine feed concentration. The performance shown in Cycle6 remained substantially the same through the 8 cycles run: Cycles 1-5,inclusive, using Mg-free brine and Cycles 6, 7 and 8 using untreatedbrine (with Mg⁺⁺ present).

EXAMPLE 3

A macroporous anion exchange resin (Dowex MWA-1) is converted to thechloride form by treatment with aqueous HCl. The resin is drained,washed with water, and drained again. The drained resin still containsabout 59.73% water.

Approximately 135 parts of the drained resin is treated with an excessof 31% aq. AlCl₃ and the excess liquid is drained off. In effect, theaq. AlCl₃ replaces the water (80.64 parts) in the resin. After drainingoff the excess aq. AlCl₃, the resin is found to weigh about 159.37 partsand by analysis, is found to contain about 39.66 parts AlCl₃. Thus, bycomputation, the resin mixture contained, at this point about 54.36parts of resin, about 39.66 parts AlCl₃ and about 65.35 parts water.

The resin mixture is then treated with about 89.5 parts of 30% NH₄ OHaq. solution; this constituted about 28% excess NH₃ over that required,theoretically, to convert the AlCl₃ to Al(OH)₃ and the resin to thebasic form. The resin is washed and drained.

EXAMPLE 4

The above resin, containing the Al(OH)₃, is treated with an aqueoussolution of LiCl in an amount to flood the resin and to provide morethan enough LiCl to complex with most, if not all, of the Al(OH)₃according to the formula LiCl.2Al(OH)₃. The mixture is heated at refluxtemperature for about 2 hours or more. After this time X-ray diffractionpatterns indicate the formation of microcrystalline LiCl.2Al(OH)₃dispersed in the resin structure.

The resin is then used to preferentially separate Li⁺ from a brinecontaining about 15.8% NaCl, about 9.1% CaCl₂ and about 305 mg/literLi⁺. This is done by passing the brine through a column-bed of theresin. After that, the Li⁺ values are eluted from the resin by using aweak solution of aq. LiCl. The cycles of brine flow and elution arerepeated numerous times without encountering a substantial loss ofcapacity in the exchange resin.

The time cycles for the brine flow and elution are established for agiven resin by determining the resin capacity, the concentration of Li⁺in the brine, and the elution factors. Once these have been establishedfor a given resin and a given brine, the process may be automaticallycycled using conventional methods and techniques known in ion exchangetechnology.

EXAMPLE 5

To 350 gms. of dry DOWEX MWA-1 (base form) is added 480 gms. AlCl₃ 6H₂ Odissolved in 410 gms. H₂ O. The mixture is prepared, with stirring, andthen substantially dried by air-blowing at ambient temperature. The"dried" mixture is found to still contain about 25.9% H₂ O.

To the mixture is added, with stirring, a solution prepared by diluting430 ml. of 30% NH₃ aqueous solution with 100 ml H₂ O. The resultingexotherm brings the mixture to about 67° C. After standing for about 1.5hours during which time the temperature drops to about 48° C., themixture is washed with 3 portions of 1000 ml. each of a saturated NaClsolution to elute excess NH₄ OH and also NH₄ Cl and Al(OH)₃ formedoutside the resin particles. After each washing step, the NaCl brine isdecanted. By analysis, it is found that 3.9% of Al₃₊ is removed by thewashings.

The resin, still moist with NaCl brine, is added to enough NaCl brine tobring the total volume to 3 liters. Then there is added 85 Gms. of dryLiCl, which dissolves, and a small amount of NH₃ is added to assure thatthe mixture is not too far on the acid side. The pH, as measured by aglass electrode with a KCl bridge, is found to be 8.3. This addition ofNH₃ is optional and is not needed if the pH is known to be above about6.5.

The mixture is then heated in a large beaker for 15 minutes during whichtime the temperature increases to about 63° C. and the pH drops to about7.06. A small amount of NH₃ is added, bringing the pH to 7.5 but NH₃comes out and the pH quickly drops to about 7.0-7.1.

The mixture is transferred to a round-bottom flask equipped with areflux condenser and heated at reflux for about 2.5 hours. The resinmixture is filtered out on a glass frit using a Buchner funnel. Thestill-moist solids are rinsed twice with 600 ml. distilled water.Analysis indicates there is about 41.7 gms. LiCl in the filtrate, andabout 8.73 gms. in the wash water, thus there is a net deposit in theresin particles of about 34.56 gms. LiCl.

In an effort to assure high loading, the resin, after drying to a watercontent of about 11.2% and a weight of about 569.3 gms., is treated witha solution prepared by dissolving 280 gms. AlCl₃.6H₂ O in 240 gms. H₂ O,stirred well, then air-dried overnight down to about 804 gms. To this isadded 250 ml. of 30% NH₃ with 50 ml. H₂ O added to it, and stirred; itexotherms to about 83° C. Then mix with 1800 ml. NaCl brine and decant.Analysis shows that 8.04 gms. of the AlCl₃.6H₂ O does not stay with theresin. 41.7 gms of LiCl in the above filtrate is enriched by adding 8gms of LiCl to it and is then mixed with the drained resin. At thispoint the total volume is about 3700 ml. with pH 7.78. The mixture isheated in a beaker to 54° C. with intermittent stirring and the pH dropsto 7.34.

The mixture is transferred back to the reflux pot and heated up toreflux within an hour and refluxed for about 80 minutes and allowed tostand and cool overnight, then filtered. Analysis for Al and Li in thefiltrate and calculations based thereon determines that the resincontains 1.37 moles Li⁺ and 3.05 moles Al³⁺. This is 0.449 Li⁺ per Al³⁺which is 89.8% of theoretical amount of Li:Al in the formulaLiCl.2Al(OH)₃. X-ray diffraction pattern indicates presence ofcrystalline LiCl.2Al(OH)₃.

The resin is transferred to a jacketed, heated exchange column, andflooded with NaCl brine (actually it is the filtrate from above andcontaining a small amount of Li⁺). Then alternate cycles of wash water(containing about 50 ppm Li⁺) and Smackover brine (pH 5.6) at a pumprate of 13 ml/min. for about 70 minutes while heating at about 90° C.The brine flooding and wash cycles are at 13 mls/min. for 27 minutes andare at ambient temperature but become heated by the column heated at 90°C. The results of the fourth full cycle, taken in 25 ml cuts, is shownbelow:

    ______________________________________                                        Cut  Li.sup.+           Cut  Li.sup.+                                         No.  mg/liter*                                                                              Remarks** No.  mg/liter*                                                                            Remarks**                                 ______________________________________                                        1    400      Start wash                                                                              10   500                                              2    430      brine     11   420                                                            coming out                                                      3    460                12   370                                              4    1560               13   333                                              5    1540               14   310                                              6    1130               15   280    start brine                               7    880                16   250                                                                                  wash coming out                           8    700                17    65                                              9    580                18    80                                              ______________________________________                                         *not adjusted for Sr.sup.++ values which interfere with Li.sup.+ analysis     but stay in the brine.                                                        **About 75 ml. hold-up in the column.                                    

EXAMPLE 6

Large particles of spodumene ore, roasted at 900°-1000° C., are groundup and screened to 35-100 mesh (U.S. Standard Sieve Size). 41.7 gms.(44.5 cc) of the screened ore is placed in the bottom of a column with across-sectional area of 1.59 cm² to a depth of 28 cm. On top of that isplaced 71.5 ml. of a resin/LiCl.2Al(OH)₃ exchange agent prepared inaccordance with the present disclosure. The bed depth of theresin/LiCl.2Al(OH)₃ is about 45 cm.

Brine (26% NaCl and containing 140 mg/liter Li⁺) is circulateddownwardly at a pump rate of about 3.2 ml/min. of flow. The column holdsabout 60 ml. of the brine and a hold-up (inventory) pot holds about 40ml., with the re-cycle lines and pump lines holding about 25 ml. Aftercirculating for 15 min. with column heated at about 95° C., the brine inthe inventory pot is found, by analysis, to contain about 500 mg/literLi⁺. The system is allowed to cool overnight.

The column is re-heated to 95° C. and circulation of the inventory brineis resumed. After 15 min. analysis shows 395 mg/liter Li⁺ ; after 30min., 430 mg/liter Li⁺, after 75 min., 630 mg/liter Li⁺ ; after 105min., 710 mg/liter Li⁺ ; and after 125 min., 730 mg/liter Li⁺.

After 130 min., 25 ml. of Smackover brine is added, bringing the totalbrine in the circulating system to about 150 ml. After 185 min. analysisshows 775 mg/liter Li⁺ ; after 220 min., analysis shows 785 mg/literLi⁺.

At this point 75 ml. of the circulating brine is removed and replacedwith 75 ml. of Smackover brine and circulation is resumed. After 10min., analysis shows 905 mg/liter Li⁺ and after 30 min, 890 mg/liter Li⁺(Li⁺ analysis is affected by Sr⁺ in the brine). The system is apparentlyat, or near equilibrium at this point, so all the inventory is removed,except that held in the column and a wash cycle of water (containingabout 180 mg/liter Li⁺) is flushed downwardly through the column at 95°C. and a pump rate of 3.2 ml/min. At start of the wash cycle 15 ml.samples are taken of the effluent. After 135 ml. of wash water is added,switch to 26% NaCl brine wash for 90 ml. 15 samples of 15 ml. eachanalyze for Li⁺ (mg/liter) as follows:

    ______________________________________                                        Sample Li.sup.+ Sample    Li.sup.+                                                                             Sample  Li.sup.+                             ______________________________________                                        1      610      6         1750   11      430                                  2      575      7         1700   12      375                                  3      580      8         1000   13      365                                  4      670      9          670   14      480                                  5      840      10         520   15      340                                  ______________________________________                                    

Recycling the 46% effluent back as influent, after 45 min. the effluentis 160 mg/liter Li⁺ ; after 60 min., 160 mg/liter Li⁺. Shut down for 2days and start up again; effluent still coming out 160 mg/liter Li⁺.After 5 hours more of recirculation, effluent is 280 mg/liter Li⁺. Runterminated.

Synthetic or natural brines containing Li⁺ values are within the purviewof the present invention and includes such natural brines as Smackoverbrines (such as found at Magnolia, Arkansas), Ludington brine (such asfound at Ludington, Mich.), Monroe brine (such as found near Midland,Mich.), and other Li-rich brines such as found at Silver Peak, Nevada,Great Salt Lake, Searles Lake (California), Dead Sea, and many others.Li⁺ - containing brines also exist in many other parts of the world,e.g., in South America.

The foregoing examples are to illustrate embodiments of the invention,but the invention is limited only by the following claims.

We claim:
 1. A particulate, anion exchange resin having suspendedtherein a microcrystalline form of LiX.2Al(OH)₃, where X is a halogen.2. The exchange resin of claim 1 wherein the resin is a macroporousresin.
 3. The composition of claim 2 wherein the macroporous exchangeresin is at least one of the group comprisingwater-insoluble,water-swellable macroporous particles of polystyrene crosslinked withdivinylbenzene and having affixed thereto amine or quaternary ammoniumgroups.
 4. The composition of claim 2 wherein the macroporous resincontains suspended therein, per cubic foot of resin, about 3 pounds toabout 12 pounds of microcrystalline LiX.2Al(OH)₃, where X = halogen. 5.A process for preparing a particulate, anion exchange resin havingmicrocrystalline LiX.2Al(OH)₃ suspended therein, where X = halogen, saidprocess comprisingimpregnating a particulate, anion exchange resin withan aqueous AlCl₃ solution, contacting the so-formed AlCl₃ - containingresin with an amount of NH₄ OH sufficient to convert the AlCl₃ toAl(OH)₃ and, if the resin is in the acid form, enough to convert theresin to the base form, contacting the so-formed Al(OH)₃ - containingresin with an aqueous solution containing lithium halide, therebyforming a lithium aluminate complex, and heating the resulting mixtureat a temperature and for a time sufficient to convert the lithiumaluminate complex to a microcrystalline structure having the formulaLiX.2Al(OH)₃, where X is a halogen.
 6. The process of claim 5 whereinthe anion exchange resin is a macroporous anion exchange resin.
 7. Theprocess of claim 5 wherein the particulate anion exchange resin is atleast one of the group comprisingwater-insoluble, water-swellableparticles of polystyrene crosslinked with divinylbenzene and havingaffixed thereto amine, or quaternary ammonium groups.
 8. The process ofclaim 7 wherein the anion exchange resin is a macroporous resin.
 9. Theprocess of claim 5 wherein the heating of the resin containing thelithium aluminate complex to convert it to microcrystallineLiX.2Al(OH)₃, where X is halogen, is done at a temperature in the rangeof about 50° C. to about reflux for a period of time of at least about 1hour.
 10. The process of claim 9 wherein the heating is done at aboutreflux temperature for more than one hour.